640 Calibration

Weigh-Tronix uses two methods for calibration. A standard or a custom calibration method. If you have a scale on a grain cart is it recommended to use the CUSTOM CALIBRATION METHOD. The vast majority of indicators purchased through Central City Scale will come calibrated out of the box. A final adjustment is usually required for most GRAIN CARTS.

For all Grain Carts use a STANDARD CONFIG number of 98 for the first two digits, this is under the CONFIG menu option. The THIRD digit is the increments of weight display. For a grain cart it is best to use a 3 for a 10 lb update or 4 for a 20 lb update or 5 for a 50 lb update. We should have the CONFIG number of 983 or 984 or 985 based off of your preference so far.

If you want to use a printer, make sure the 4th digit on the CONFIG number is a 9. For Example the CONFIG number so far could be 9839, 9849,9859 at this point.

The last placeholder should be a zero. The Final CONFIG number should be 98300 or 98390 or 98400 or 98490 or 98500 0r 98590. Once again the 9 is set up as a print command. It does not hurt anything is you have the 9 in the CONFIG number.

The CUSTOM NUMBER for calibration can be found on page 16 of your 640 M manual. One thing to note on the Central City Scale System in a 3 bar grain cart can weight out as a 4 bar system, because of the resistor in the junction box on some units. With the resistor involved your CUSTOM NUMBER should be 37500 to begin with. If you do not have the resistor the CUSTOM NUMBER would be 27775. The grain cart systems are labeled as 2-1/4 Dual bars. The easiest way to tell if you have a resistor or not is to identify if the junction box has external 5 pin plugs. If it has the plugs it would weigh out at 4 of the 2-1/4 dual weigh bars. You then would use the CUSTOM NUMBER of 37500. If the wires for the junction box are hard wired into the junction box you would use the CUSTOM NUMBER of 27775. All 5 weigh bar Weigh-Tronix systems do not use the resistor so a typical starting point for this scenario would be 98590 for the CONFIG and a CUSTOM of 45000.

The easiest way to see if you have the correct CUSTOM NUMBER is to stand on the hitch while it is hitched up to the tractor. (It will not read accurately if the jack stand is being used.) If the weight is off you can use the formula below to adjust the CUSTOM NUMBER. The videos below will also help guide you through the process.

CALIBRATION FORULA = ACUTAL WEIGHT ÷ BY INCORRECT WEIGHT X THE CUSTOM NUMBER. One thing to note is that the custom number is just a starting point and not a constant. As you get closer to the correct weight the CUSTOM NUMBER will stabilize within 1% or so.

EXAMPLE Truck goes to a certified scale and reads 58,654 lbs and the grain cart gave a reading of 59,240 lbs.

Let's say we have a 3 bar Weigh-Tronix grain cart system with a junction box that has a resistor. Our current numbers would be 98390 for the CONFIG ( remains) and 37500 for the CUSTOM NUMBER.

ACTUAL = 58,654 ÷ 59,240 =.99010804 therefore 37500 x .99= 37129 is the NEW CUSTOM NUMBER. You make want to do a few more calibrations to verify the accuracy.

Digi-Star Calibration GT 400 and most other indicators

The Digi-Star uses a SETUP NUMBER and a CAL NUMBER for it's calibration. An example of a SETUP NUMBER would be 127080.
Let's break down the SETUP NUMBER. The first Digit of (1) should be used because of the standard weighing dynamic.

The second digit would be used for the rate of gain, and a (2) is recommended for Grain Cart weighing.

The third digit (7) relates to the increment size and a 7 would be 20 LBS. A 6 would be 10 LBS, 7 would be 20 LBS, 8 would be 50 LBS, and 9 would be 100LBS. This can be adjust to how it suits you best.

The last three digits (080) refer to the overall capacity in thousands of LBS. For this instance the indicator would be set up with a capacity of 80,000 LBS. If you want to changed the capacity to 100,000 LBS you would simple change the last three digits to 100.

Digi-Star uses a CAL NUMBER for it's calibration method. A 3 bar Digi-Star system should typically have a SETUP NUMBER of 127080 and a CAL NUMBER 24000. If it is a 5 bar Digi-Star system you might have 40000 for the CAL NUMBER.

CALIBRATION FORULA = ACUTAL WEIGHT ÷ BY INCORRECT WEIGHT X THE CAL NUMBER. One thing to note is that the custom number is just a starting point and not a constant. As you get closer to the correct weight the CUSTOM NUMBER will stabilize within 1% or so.

EXAMPLE Truck goes to a certified scale and reads 58,654 lbs and the grain cart gave a reading of 59,240 lbs.

Let's say we have a 3 bar Digi-Star grain cart system. Our current numbers would be 127080 for the SETUP( remains) and 24000 for the CAL NUMBER.

ACTUAL = 58,654 ÷ 59,240 =.99010804 therefore 24000 x .99= 23760 is the NEW CAL NUMBER. You make want to do a few more calibrations to verify the accuracy.

Libra Cart Calibration

If upgrading from an existing scale indicator, use 0.40 mV/V as the Sensitivity, and the indicator's calibration number as the Rated Capacity. We also use this method for the initial set up. We will have the Libra calibrated before it is shipped. If you provide the CAL NUMBER or CUSTOM NUMBER we can have it all saved on to the device before hand. This method works for Digi-Star and Weigh-Tronix.

The CUSTOM NUMBER /CAL NUMBER = RATED CAPACITY.WHEN .4 mV/V IS USED THE RATED CAPACITY BECOMES A CUSTOM NUMBER.

DIGI-STAR USES A CAL NUMBER AND WEIGH TRONIX USES A CUSTOM NUMBER

One thing to note on the Central City Scale System in a 3 bar grain cart can weight out as a 4 bar system, because of the resistor in the junction box on some units. With the resistor involved your CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY should be 37500 to begin with. If you do not have the resistor the CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY it would be 27775. The grain cart systems are labeled as 2-1/4 Dual bars. The easiest way to tell if you have a resistor or not is to identify if the junction box has external 5 pin plugs. If it has the plugs it would weigh out at 4 of the 2-1/4 dual weigh bars. You then would use the CUSTOM NUMBER/RATED CAPACITY of 37500. If the wires for the junction box are hard wired into the junction box you would use the CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY of 27775. All 5 weigh bar Weigh-Tronix systems do not use the resistor so a typical starting point for this scenario would be .4mV/V for the Sensitivity and a CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY of 45000. Digi-Star 3 bar or 3 point with compression cells would be 24000 for the CAL NUMBER/RATED CAPACITY. Digi-Star 5 Bar scales would be 40000 for the CAL NUMBER/RATED CAPACITY.

The easiest way to see if you have the correct CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY is to stand on the hitch while it is hitched up to the tractor. (It will not read accurately if the jack stand is being used.) If the weight is off you can use the formula below to adjust the CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY The videos below will also help guide you through the process.

CALIBRATION FORULA = ACUTAL WEIGHT ÷ BY INCORRECT WEIGHT X THE CUSTOM NUMBER/RATED CAPACITY. One thing to note is that the custom number is just a starting point and not a constant. As you get closer to the correct weight the CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY will stabilize within 1% or so.

EXAMPLE Truck goes to a certified scale and reads 58,654 LBS and the grain cart gave a reading of 59,240 LBS.

Let's say we have a 3 bar Weigh-Tronix grain cart system with a junction box that has a resistor. Our current number would be 37500 for the CAL NUMBER or CUSTOM NUMBER/RATED CAPACITY.

ACTUAL = 58,654 ÷ 59,240 =.99010804 therefore 37500 x .99= 37129 is the CAL NUMBER or NEW CUSTOM NUMBER/RATED CAPACITY. You make want to do a few more calibrations to verify the accuracy.